Audiences and Multiple Workspaces (Do we need both?)

With the recent addition of audiences is there a need for multiple workspaces outside of maybe a dev, test, and production environment? It seems like you could disable workspace access and only allow app access. Then allow AD groups to fully dictate "group level security" based off of an applied audience filter. Then attach AD groups to specific datasets to allow individuals to build on top of them. Trying to better understand the benefits of multiple department workspaces vs the new audience applied department worksapce. Any advice or articles would be extremely helpful my organization is setting up a foundation of which to build on.